Together, the alliance accounts for 122 million fixed-line and 23 mobile phone customers. The group is encouraging other operators to join. Around 15 operators have already expressed interest, according to the statement.

The alliance members have pledged to share information and expertise on converged fixed-mobile services and work jointly on common standards.

The group’s vision is for people to use one phone with one number, address book and voicemail bank, taking advantage of cheap, high-speed connectivity in their fixed-line home or office setting, while enjoying mobility outside in the wide-area cell phone network, said Steve Andrews, chief of BT’s mobility and convergence unit, in an interview last month.

Initially, development work will focus on 3G (third-generation) handsets with Bluetooth capability, according to Andrews. These phones will allow users at home or in the office to link to Bluetooth base stations with their fixed broadband connections, and to roam onto mobile networks when outside the Bluetooth footprint. Data speeds up to 700Kbps will be possible in the wireless Bluetooth cell, where calls could also be priced at normal fixed-line rates or lower, he said.

Bluetooth will be the technology of choice until 3G phones with Wi-Fi capability become available at prices comparable for high-end mobile phones, according to Andrews. Most operators, he said, don’t expect availability of high-end, well-priced handsets with Wi-Fi capability for another 18 months to two years.